Today's Phys. Rev Letter [GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2][1] shows the analysis of the third confirmed detection of a black hole (BH) merger by the LIGO collaboration. According to the paper this even may differ from the previous two:

>The black hole spins are best constrained through measurement of the effective inspiral spin parameter, a mass-weighted combination of the spin components perpendicular to the orbital plane, $\chi_{eff} = -0.12^{+0.21}_{-0.30}$.  This result implies that spin configurations with both component spins positively aligned with the orbital angular momentum are disfavored. 

If I understand correctly, while there is significant pre-processing in frequency space, the final data for each site is really only the one-dimensional strain versus time plot, and *all extracted parameters from the event* come from the maximum-likelihood fitting of theoretically generated strain waveforms to these two plots for the two LIGO sites.

A great deal of work has gone in to the statistical analysis of these events, both for low latency detection (alerts to the community for possible coincident optical detection) and more careful analysis later. The fact that $\chi_{eff}$ is so many error bars away from unity suggest there is a good chance the spins were not aligned to the orbit.

While I can see the current open access PRL, I don't have ready access to many of the references. Have there been any plots showing how much worse the fit would have been if the spins were aligned in the simulation?

In addition to statements of statistical significance of an effect, "show me" plots are often shown by scientist to convey visually how the fit might differ if the effect weren't happening. Has one been released in this case showing the best fit using an aligned spin assumption, or might it be forthcoming?

[![enter image description here][2]][2]

**above:** Enlarged, cropped section of Figure 1, shown below.

[![enter image description here][5]][5]

[![enter image description here][6]][6]

**above:** [Figure 1][1].

[![enter image description here][7]][7]

**above:** Enlarged, cropped section of Figure 1, residual plot is shown with a vertical scale 25% smaller than the data.

  [1]: https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.118.221101
  [2]: https://i.sstatic.net/cJcwC.png
  [3]: https://i.sstatic.net/vuX5f.png
  [4]: https://i.sstatic.net/h7mdN.png
  [5]: https://i.sstatic.net/yld7i.png
  [6]: https://i.sstatic.net/c0XUS.png
  [7]: https://i.sstatic.net/W2gH8.png